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Title:Low-temperature thermal expansion of amorphous solids
Author(s):Ackerman, David Alan
Doctoral Committee Chair(s):Anderson, A.C.
Department / Program:Physics
Subject(s):low-temperature thermal expansion
amorphous solids
specific heat
thermal conductivity
ultrasonic dispersion
Abstract:For most amorphous materials at temperatures below ~ 1 K, the magnitudes and temperature dependences of specific heat, thermal conductivity and ultrasonic dispersion are qualitatively similar, independent of chemical composition. It has been suggested that thermal expansion also exhibits this universal behavior. The development of a dilatometer cap- 12 able of resolving sample strains as small as 10 has permitted measurement of the linear thermal expansion of various glasses below 1 K. These investigations ha\"e demonstrated, however, that the low-temperature thermal expansion coefficient of glasses can be positive, negative, large or small. analysis of measurements performed. on two types of vitreous silica, two amorphous polymers, As2S3 and Zr02 : Y 203 is presented in the context of the phenonenclogical tunneling-states model Consistency in explanation of thermal expansion and ultrasonic behavior maintained by assuming a broad, weakly energy-dependent distribution of coupling strengths between phonons and the localized excitations thought to be characteristic of the glassy state.
Issue Date:1982
Genre:Dissertation / Thesis
Rights Information:Copyright 1982 David Alan Ackerman
Date Available in IDEALS:2011-06-13
Identifier in Online Catalog:19409

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